1. Field of Invention
The invention relates to a liquid drop discharge apparatus for applying liquid drops onto a substrate placed on a stage, more specifically to a liquid drop discharge apparatus having a mechanism of controlling its flushing operation and a driving method of the same, further an apparatus and a method for film deposition, a method for forming a color filter, a method for fabricating an organic electroluminescent device, and an electronic device.
2. Description of Related Art
As a liquid drop discharge apparatus for discharging liquid drops of ink and the like for thin film deposition and patterning, there is an apparatus to which inkjet techniques is applied in general. This apparatus has a liquid drop discharge head for receiving the feed of a liquid material from a liquid material feeding part and a stage for relatively moving a substrate to the liquid drop discharge head, which allows liquid drops to be discharged onto the substrate while moving the liquid drop discharge head based on discharge data for thin film deposition and patterning.
In such a device, the liquid drop discharge head can be mounted on a carriage disposed on the stage to be movable to the stage in the X-direction, for example. In addition, the stage is provided with a transport mechanism for transporting the substrate in the Y-direction, for example. Therefore, the liquid drop discharge head is relatively movable in the X- and Y-direction to the substrate.
Furthermore, the liquid drop discharge head can be a rectangle in a plane, in which multiple nozzles for discharging liquid drops onto the substrate are arranged lengthwise and crosswise, such as in a matrix or array. A shaft for supporting the liquid drop discharge head is disposed rotatably by a rotating unit, which allows discharging liquid drops in the position that the rows of nozzles are oblique toward the X-direction and the Y-direction. Here, setting the rows of the nozzles oblique for discharging liquid drops is that the pitch between the adjacent nozzles constantly formed is virtually narrowed to conduct fine, or continuous thin film deposition and patterning.
More specifically, as shown in FIG. 15(a), when liquid drops are discharged in the normal position that rows L of nozzles N of a liquid drop discharge head H are orthogonal to the direction of moving them (the X-direction), the pitch P2 between the liquid drops T to be discharged becomes equal to the pitch P1 between the nozzles N and N.
On the other hand, as shown in FIG. 15(b), when liquid drops are discharged in the position that the rows L of the nozzles N of the liquid drop discharge head H are set oblique toward the direction of moving them (the X-direction), the pitch P3 between the liquid drops T to be discharged becomes narrower than the pitch P1 between the nozzles N and N. Consequently, the pitch between the nozzles can be virtually narrowed.
In the meantime, in this apparatus, when the volatility of a solvent in a liquid material to be discharged is particularly high, nozzles not continuously discharging the liquid material cause an increase in viscosity in the liquid material held in the openings due to the volatilized solvent. In the extreme case, there have been problems that the liquid material is set, dust and dirt are attached here, or air bubbles are mixed, which generate clogging in the nozzle openings to cause discharge failures.